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incubator-nuttx/drivers/net/telnet.c

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/****************************************************************************
* drivers/net/telnet.c
*
* Copyright (C) 2007, 2009, 2011-2013, 2017, 2019, 2020 Gregory Nutt. All
* rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* This derives remotely from some Telnet logic from uIP which has a
* compatible BSD license:
*
* Author: Adam Dunkels <adam@sics.se>
* Copyright (c) 2003, Adam Dunkels.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute, NuttX nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <assert.h>
#include <stdio.h>
#include <fcntl.h>
#include <poll.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/kthread.h>
#include <nuttx/signal.h>
#include <nuttx/semaphore.h>
#include <nuttx/fs/fs.h>
#include <nuttx/net/net.h>
#include <nuttx/net/telnet.h>
#ifdef CONFIG_NETDEV_TELNET
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
#ifndef CONFIG_TELNET_RXBUFFER_SIZE
# define CONFIG_TELNET_RXBUFFER_SIZE 256
#endif
#ifndef CONFIG_TELNET_TXBUFFER_SIZE
# define CONFIG_TELNET_TXBUFFER_SIZE 256
#endif
#ifndef CONFIG_TELNET_MAXLCLIENTS
# define CONFIG_TELNET_MAXLCLIENTS 8
#endif
#ifndef CONFIG_TELNET_IOTHREAD_PRIORITY
# define CONFIG_TELNET_IOTHREAD_PRIORITY 100
#endif
#ifndef CONFIG_TELNET_IOTHREAD_STACKSIZE
# define CONFIG_TELNET_IOTHREAD_STACKSIZE 1024
#endif
#undef HAVE_SIGNALS
#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGSTP)
# define HAVE_SIGNALS
#endif
/* Telnet protocol stuff ****************************************************/
#define TELNET_NL 0x0a
#define TELNET_CR 0x0d
/* Telnet commands */
#define TELNET_ECHO 1
#define TELNET_SGA 3 /* Suppress Go Ahead */
#define TELNET_NAWS 31 /* Negotiate about window size */
/* Telnet control */
#define TELNET_IAC 255
#define TELNET_WILL 251
#define TELNET_WONT 252
#define TELNET_DO 253
#define TELNET_DONT 254
#define TELNET_SB 250
#define TELNET_SE 240
/* Device stuff *************************************************************/
#define TELNET_DEVFMT "/dev/telnet%d"
/****************************************************************************
* Private Types
****************************************************************************/
/* The state of the telnet parser */
enum telnet_state_e
{
STATE_NORMAL = 0,
STATE_IAC,
STATE_WILL,
STATE_WONT,
STATE_DO,
STATE_DONT,
STATE_SB,
STATE_SB_NAWS,
STATE_SE
};
/* This structure describes the internal state of the driver */
struct telnet_dev_s
{
sem_t td_exclsem; /* Enforces mutually exclusive access */
sem_t td_iosem; /* I/O thread will notify that data is available */
uint8_t td_state; /* (See telnet_state_e) */
uint8_t td_pending; /* Number of valid, pending bytes in the rxbuffer */
uint8_t td_offset; /* Offset to the valid, pending bytes in the rxbuffer */
uint8_t td_crefs; /* The number of open references to the session */
uint8_t td_minor; /* Minor device number */
#ifdef CONFIG_TELNET_SUPPORT_NAWS
uint16_t td_rows; /* Number of NAWS rows */
uint16_t td_cols; /* Number of NAWS cols */
int td_sb_count; /* Count of TELNET_SB bytes received */
#endif
#ifdef HAVE_SIGNALS
pid_t td_pid;
#endif
struct pollfd td_fds;
FAR struct socket td_psock; /* A clone of the internal socket structure */
char td_rxbuffer[CONFIG_TELNET_RXBUFFER_SIZE];
char td_txbuffer[CONFIG_TELNET_TXBUFFER_SIZE];
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* Support functions */
#ifdef CONFIG_TELNET_DUMPBUFFER
static inline void telnet_dumpbuffer(FAR const char *msg,
FAR const char *buffer, unsigned int nbytes);
#else
# define telnet_dumpbuffer(msg,buffer,nbytes)
#endif
static void telnet_getchar(FAR struct telnet_dev_s *priv, uint8_t ch,
FAR char *dest, int *nread);
static ssize_t telnet_receive(FAR struct telnet_dev_s *priv,
FAR const char *src, size_t srclen, FAR char *dest,
size_t destlen);
static bool telnet_putchar(FAR struct telnet_dev_s *priv, uint8_t ch,
int *nwritten);
static void telnet_sendopt(FAR struct telnet_dev_s *priv, uint8_t option,
uint8_t value);
static int telnet_io_main(int argc, FAR char** argv);
/* Telnet character driver methods */
static int telnet_open(FAR struct file *filep);
static int telnet_close(FAR struct file *filep);
static ssize_t telnet_read(FAR struct file *filep, FAR char *buffer,
size_t len);
static ssize_t telnet_write(FAR struct file *filep, FAR const char *buffer,
size_t len);
static int telnet_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
static int telnet_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup);
/* Telnet session creation */
static int telnet_session(FAR struct telnet_session_s *session);
/* Telnet factory driver methods */
static ssize_t factory_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t factory_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int factory_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_telnet_fops =
{
telnet_open, /* open */
telnet_close, /* close */
telnet_read, /* read */
telnet_write, /* write */
NULL, /* seek */
telnet_ioctl, /* ioctl */
telnet_poll /* poll */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, NULL /* unlink */
#endif
};
static const struct file_operations g_factory_fops =
{
NULL, /* open */
NULL, /* close */
factory_read, /* read */
factory_write, /* write */
NULL, /* seek */
factory_ioctl, /* ioctl */
NULL /* poll */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, NULL /* unlink */
#endif
};
/* This is an global data set of all of all active Telnet drivers. This
* additional logic in included to handle killing of task via control
* characters received via Telenet (via Ctrl-C SIGINT, in particular).
*/
static pid_t g_telnet_io_kthread;
static struct telnet_dev_s *g_telnet_clients[CONFIG_TELNET_MAXLCLIENTS];
static sem_t g_iosem = SEM_INITIALIZER(0);
static sem_t g_clients_sem = SEM_INITIALIZER(1);
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: telnet_dumpbuffer
*
* Description:
* Dump a buffer of data (debug only)
*
****************************************************************************/
#ifdef CONFIG_TELNET_DUMPBUFFER
static inline void telnet_dumpbuffer(FAR const char *msg,
FAR const char *buffer,
unsigned int nbytes)
{
/* CONFIG_DEBUG_FEATURES, CONFIG_DEBUG_INFO, and CONFIG_DEBUG_NET have to
* be defined or the following does nothing.
*/
ninfodumpbuffer(msg, (FAR const uint8_t *)buffer, nbytes);
}
#endif
/****************************************************************************
* Name: telnet_check_ctrlchar
*
* Description:
* Check if an incoming control character should generate a signal.
*
****************************************************************************/
#ifdef HAVE_SIGNALS
static void telnet_check_ctrlchar(FAR struct telnet_dev_s *priv,
FAR char *buffer, size_t len)
{
int signo = 0;
for (; priv->td_pid >= 0 && len > 0; buffer++, len--)
{
#ifdef CONFIG_TTY_SIGINT
/* Is this the special character that will generate the SIGINT signal? */
if (*buffer == CONFIG_TTY_SIGINT_CHAR)
{
/* Yes.. note that the kill is needed and do not put the character
* into the Rx buffer. It should not be read as normal data.
*/
signo = SIGINT;
break;
}
#endif
#ifdef CONFIG_TTY_SIGSTP
/* Is this the special character that will generate the SIGSTP signal? */
if (*buffer == CONFIG_TTY_SIGSTP_CHAR)
{
/* Note that the kill is needed and do not put the character
* into the Rx buffer. It should not be read as normal data.
*/
signo = SIGSTP;
#ifndef CONFIG_TTY_SIGINT
break;
#endif
}
#endif
}
/* Send the signal if necessary */
if (signo != 0)
{
nxsig_kill(priv->td_pid, signo);
}
}
#endif
/****************************************************************************
* Name: telnet_getchar
*
* Description:
* Get another character for the user received buffer from the RX buffer
*
****************************************************************************/
static void telnet_getchar(FAR struct telnet_dev_s *priv, uint8_t ch,
FAR char *dest, int *nread)
{
register int index;
#ifndef CONFIG_TELNET_CHARACTER_MODE
/* Ignore carriage returns */
if (ch != TELNET_CR)
#endif
{
/* Add all other characters to the destination buffer */
index = *nread;
dest[index++] = ch;
*nread = index;
}
}
/****************************************************************************
* Name: telnet_receive
*
* Description:
* Process a received Telnet buffer
*
****************************************************************************/
static ssize_t telnet_receive(FAR struct telnet_dev_s *priv,
FAR const char *src, size_t srclen,
FAR char *dest, size_t destlen)
{
int nread;
uint8_t ch;
ninfo("srclen: %d destlen: %d\n", srclen, destlen);
for (nread = 0; srclen > 0 && nread < destlen; srclen--)
{
ch = *src++;
ninfo("ch=%02x state=%d\n", ch, priv->td_state);
switch (priv->td_state)
{
case STATE_IAC:
if (ch == TELNET_IAC)
{
telnet_getchar(priv, ch, dest, &nread);
priv->td_state = STATE_NORMAL;
}
else
{
switch (ch)
{
case TELNET_WILL:
priv->td_state = STATE_WILL;
break;
case TELNET_WONT:
priv->td_state = STATE_WONT;
break;
case TELNET_DO:
priv->td_state = STATE_DO;
break;
case TELNET_DONT:
priv->td_state = STATE_DONT;
break;
#ifdef CONFIG_TELNET_SUPPORT_NAWS
case TELNET_SB:
priv->td_state = STATE_SB;
priv->td_sb_count = 0;
break;
case TELNET_SE:
priv->td_state = STATE_NORMAL;
break;
#endif
default:
priv->td_state = STATE_NORMAL;
break;
}
}
break;
case STATE_WILL:
#ifdef CONFIG_TELNET_SUPPORT_NAWS
/* For NAWS, Reply with a DO */
if (ch == TELNET_NAWS)
{
telnet_sendopt(priv, TELNET_DO, ch);
}
/* Reply with a DON'T */
else
#endif
{
telnet_sendopt(priv, TELNET_DONT, ch);
ninfo("Suppress: 0x%02X (%d)\n", ch, ch);
}
priv->td_state = STATE_NORMAL;
break;
case STATE_WONT:
telnet_sendopt(priv, TELNET_DONT, ch);
priv->td_state = STATE_NORMAL;
break;
case STATE_DO:
#ifdef CONFIG_TELNET_CHARACTER_MODE
if (ch == TELNET_SGA || ch == TELNET_ECHO)
{
/* If it received 'ECHO' or 'Suppress Go Ahead', then do nothing */
}
else
{
/* Reply with a WONT */
telnet_sendopt(priv, TELNET_WONT, ch);
ninfo("WONT: 0x%02X\n", ch);
}
#else
/* Reply with a WONT */
telnet_sendopt(priv, TELNET_WONT, ch);
#endif
priv->td_state = STATE_NORMAL;
break;
case STATE_DONT:
/* Reply with a WONT */
telnet_sendopt(priv, TELNET_WONT, ch);
priv->td_state = STATE_NORMAL;
break;
case STATE_NORMAL:
if (ch == TELNET_IAC)
{
priv->td_state = STATE_IAC;
}
else
{
telnet_getchar(priv, ch, dest, &nread);
}
break;
#ifdef CONFIG_TELNET_SUPPORT_NAWS
/* Handle Telnet Sub negotiation request */
case STATE_SB:
switch (ch)
{
case TELNET_NAWS:
priv->td_state = STATE_SB_NAWS;
break;
default:
priv->td_state = STATE_NORMAL;
break;
}
break;
/* Handle NAWS sub-option negotiation */
case STATE_SB_NAWS:
/* Update cols / rows based on received byte count */
switch (priv->td_sb_count)
{
case 0:
priv->td_cols = (priv->td_cols & 0x00ff) | (ch << 8);
break;
case 1:
priv->td_cols = (priv->td_cols & 0xff00) | ch;
break;
case 2:
priv->td_rows = (priv->td_rows & 0x00ff) | (ch << 8);
break;
case 3:
priv->td_rows = (priv->td_rows & 0xff00) | ch;
ninfo("NAWS: %d,%d", priv->td_cols, priv->td_rows);
break;
}
/* Increment SB count and switch to NORMAL when complete */
if (++priv->td_sb_count == 4)
{
priv->td_state = STATE_NORMAL;
}
break;
#endif
}
}
/* We get here if (1) all of the received bytes have been processed, or
* (2) if the user's buffer has become full.
*/
if (srclen > 0)
{
/* Remember where we left off. These bytes will be returned the next
* time that telnet_read() is called.
*/
priv->td_pending = srclen;
priv->td_offset = (src - priv->td_rxbuffer);
}
else
{
/* All of the received bytes were consumed */
priv->td_pending = 0;
priv->td_offset = 0;
}
return nread;
}
/****************************************************************************
* Name: telnet_putchar
*
* Description:
* Put another character from the user buffer to the TX buffer.
*
****************************************************************************/
static bool telnet_putchar(FAR struct telnet_dev_s *priv, uint8_t ch,
int *nread)
{
register int index;
bool ret = false;
/* Ignore carriage returns (we will put these in automatically as necessary) */
if (ch != TELNET_CR)
{
/* Add all other characters to the destination buffer */
index = *nread;
priv->td_txbuffer[index++] = ch;
/* Check for line feeds */
if (ch == TELNET_NL)
{
/* Now add the carriage return */
priv->td_txbuffer[index++] = TELNET_CR;
/* End of line */
ret = true;
}
*nread = index;
}
return ret;
}
/****************************************************************************
* Name: telnet_sendopt
*
* Description:
* Send the telnet option bytes
*
****************************************************************************/
static void telnet_sendopt(FAR struct telnet_dev_s *priv, uint8_t option,
uint8_t value)
{
uint8_t optbuf[3];
int ret;
optbuf[0] = TELNET_IAC;
optbuf[1] = option;
optbuf[2] = value;
telnet_dumpbuffer("Send optbuf", optbuf, 3);
ret = psock_send(&priv->td_psock, optbuf, 3, 0);
if (ret < 0)
{
nerr("ERROR: Failed to send TELNET_IAC: %d\n", ret);
}
}
/****************************************************************************
* Name: telnet_open
****************************************************************************/
static int telnet_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
int tmp;
int ret;
ninfo("td_crefs: %d\n", priv->td_crefs);
/* Get exclusive access to the device structures */
ret = nxsem_wait(&priv->td_exclsem);
if (ret < 0)
{
nerr("ERROR: nxsem_wait failed: %d\n", ret);
goto errout;
}
/* Increment the count of references to the device. If this the first
* time that the driver has been opened for this device, then initialize
* the device.
*/
tmp = priv->td_crefs + 1;
if (tmp > 255)
{
/* More than 255 opens; uint8_t would overflow to zero */
ret = -EMFILE;
goto errout_with_sem;
}
/* Save the new open count on success */
priv->td_crefs = tmp;
ret = OK;
errout_with_sem:
nxsem_post(&priv->td_exclsem);
errout:
return ret;
}
/****************************************************************************
* Name: telnet_close
****************************************************************************/
static int telnet_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
FAR char *devpath;
int ret;
int i;
ninfo("td_crefs: %d\n", priv->td_crefs);
/* Get exclusive access to the device structures */
ret = nxsem_wait(&priv->td_exclsem);
if (ret < 0)
{
nerr("ERROR: nxsem_wait failed: %d\n", ret);
goto errout;
}
/* Decrement the references to the driver. If the reference count will
* decrement to 0, then uninitialize the driver.
*/
if (priv->td_crefs > 1)
{
/* Just decrement the reference count and release the semaphore */
priv->td_crefs--;
nxsem_post(&priv->td_exclsem);
}
else
{
/* Re-create the path to the driver. */
ret = asprintf(&devpath, TELNET_DEVFMT, priv->td_minor);
if (ret < 0)
{
nerr("ERROR: Failed to allocate the driver path\n");
}
else
{
/* Un-register the character driver */
ret = unregister_driver(devpath);
if (ret < 0)
{
/* NOTE: a return value of -EBUSY is not an error, it simply
* means that the Telnet driver is busy now and cannot be
* registered now because there are other sessions using the
* connection. The driver will be properly unregistered when
* the final session terminates.
*/
if (ret != -EBUSY)
{
nerr("ERROR: Failed to unregister the driver %s: %d\n",
devpath, ret);
}
else
{
ret = OK;
}
}
kmm_free(devpath);
}
/* Remove ourself from the clients list */
nxsem_wait(&g_clients_sem);
for (i = 0; i < CONFIG_TELNET_MAXLCLIENTS; i++)
{
if (g_telnet_clients[i] == priv)
{
g_telnet_clients[i] = NULL;
break;
}
}
/* If the socket is still polling */
if (priv->td_fds.events)
{
/* Tear down the poll */
psock_poll(&priv->td_psock, &priv->td_fds, FALSE);
priv->td_fds.events = 0;
}
nxsem_post(&g_clients_sem);
/* Notify the I/O thread that a client was removed */
nxsem_post(&g_iosem);
/* Close the socket */
psock_close(&priv->td_psock);
/* Release the driver memory. What if there are threads waiting on
* td_exclsem? They will never be awakened! How could this happen?
* crefs == 1 so there are no other open references to the driver.
* But this could have if someone were trying to re-open the driver
* after every other thread has closed it. That really should not
* happen in the intended usage model.
*/
DEBUGASSERT(priv->td_exclsem.semcount == 0);
nxsem_destroy(&priv->td_exclsem);
kmm_free(priv);
}
errout:
return ret;
}
/****************************************************************************
* Name: telnet_read
****************************************************************************/
static ssize_t telnet_read(FAR struct file *filep, FAR char *buffer,
size_t len)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
ssize_t nread = 0;
int ret;
ninfo("len: %d\n", len);
/* First, handle the case where there are still valid bytes left in the
* I/O buffer from the last time that read was called. NOTE: Much of
* what we read may be protocol stuff and may not correspond to user
* data. Hence we need the loop and we need may need to wait for data
* multiple times in order to get data that the client is interested in.
*/
do
{
FAR const char *src;
if (priv->td_pending == 0)
{
/* poll fds.revents contains last poll status in case of error */
if ((priv->td_fds.revents & (POLLHUP | POLLERR)) != 0)
{
return -EPIPE;
}
if (filep->f_oflags & O_NONBLOCK)
{
return -EAGAIN;
}
/* Wait for new data, interrupt, or thread cancellation */
ret = nxsem_wait(&priv->td_iosem);
if (ret < 0)
{
nerr("ERROR: nxsem_wait failed: %d\n", ret);
return (ssize_t)ret;
}
continue;
}
/* Take exclusive access to data buffer */
ret = nxsem_wait(&priv->td_exclsem);
if (ret < 0)
{
nerr("ERROR: nxsem_wait failed: %d\n", ret);
return (ssize_t)ret;
}
/* Process the buffered telnet data */
src = &priv->td_rxbuffer[priv->td_offset];
nread = telnet_receive(priv, src, priv->td_pending, buffer, len);
nxsem_post(&priv->td_exclsem);
}
while (nread == 0);
/* Returned Value:
*
* nread > 0: The number of characters copied into the user buffer by
* telnet_receive().
* nread <= 0: Loss of connection or error events reported by recv().
*/
return nread;
}
/****************************************************************************
* Name: telnet_write
****************************************************************************/
static ssize_t telnet_write(FAR struct file *filep, FAR const char *buffer,
size_t len)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
FAR const char *src = buffer;
ssize_t nsent;
ssize_t ret;
int ncopied;
char ch;
bool eol;
ninfo("len: %d\n", len);
/* Process each character from the user buffer */
for (nsent = 0, ncopied = 0; nsent < len; nsent++)
{
/* Get the next character from the user buffer */
ch = *src++;
/* Add the character to the TX buffer */
eol = telnet_putchar(priv, ch, &ncopied);
/* Was that the end of a line? Or is the buffer too full to hold the
* next largest character sequence ("\r\n")?
*/
if (eol || ncopied > CONFIG_TELNET_TXBUFFER_SIZE - 2)
{
/* Yes... send the data now */
ret = psock_send(&priv->td_psock, priv->td_txbuffer, ncopied, 0);
if (ret < 0)
{
nerr("ERROR: psock_send failed '%s': %d\n",
priv->td_txbuffer, ret);
return ret;
}
/* Reset the index to the beginning of the TX buffer. */
ncopied = 0;
}
}
/* Send anything remaining in the TX buffer */
if (ncopied > 0)
{
ret = psock_send(&priv->td_psock, priv->td_txbuffer, ncopied, 0);
if (ret < 0)
{
nerr("ERROR: psock_send failed '%s': %d\n",
priv->td_txbuffer, ret);
return ret;
}
}
/* Notice that we don't actually return the number of bytes sent, but
* rather, the number of bytes that the caller asked us to send. We may
* have sent more bytes (because of CR-LF expansion). But it confuses
* some logic if you report that you sent more than you were requested to.
*/
return len;
}
/****************************************************************************
* Name: telnet_session
*
* Description:
* Create a character driver to "wrap" the telnet session. This function
* will select and return a unique path for the new telnet device.
*
* Input Parameters:
* session - On input, contains the socket descriptor that represents the
* new telnet connection. On output, it holds the path to the new Telnet
* driver.
*
* Returned Value:
* Zero (OK) on success; a negated errno value on failure.
*
****************************************************************************/
static int telnet_session(FAR struct telnet_session_s *session)
{
FAR struct telnet_dev_s *priv;
FAR struct socket *psock;
int ret;
/* Allocate instance data for this driver */
priv = (FAR struct telnet_dev_s *)kmm_zalloc(sizeof(struct telnet_dev_s));
if (!priv)
{
nerr("ERROR: Failed to allocate the driver data structure\n");
return -ENOMEM;
}
/* Initialize the allocated driver instance */
nxsem_init(&priv->td_exclsem, 0, 1);
nxsem_init(&priv->td_iosem, 0, 0);
/* td_iosem is used for signaling and, hence, must not participate in
* priority inheritance.
*/
nxsem_setprotocol(&priv->td_iosem, SEM_PRIO_NONE);
priv->td_state = STATE_NORMAL;
priv->td_crefs = 0;
priv->td_minor = 0;
priv->td_pending = 0;
priv->td_offset = 0;
#ifdef HAVE_SIGNALS
priv->td_pid = -1;
#endif
#ifdef CONFIG_TELNET_SUPPORT_NAWS
priv->td_rows = 25;
priv->td_cols = 80;
priv->td_sb_count = 0;
#endif
/* Clone the internal socket structure. We do this so that it will be
* independent of threads and of socket descriptors (the original socket
* instance resided in the daemon's task group`).
*/
psock = sockfd_socket(session->ts_sd);
if (!psock)
{
nerr("ERROR: Failed to convert sd=%d to a socket structure\n",
session->ts_sd);
ret = -EINVAL;
goto errout_with_dev;
}
ret = psock_dup2(psock, &priv->td_psock);
if (ret < 0)
{
nerr("ERROR: psock_dup2 failed: %d\n", ret);
goto errout_with_dev;
}
/* Allocate a unique minor device number of the telnet driver.
* Get exclusive access to the minor counter.
*/
ret = nxsem_wait_uninterruptible(&g_clients_sem);
if (ret < 0)
{
nerr("ERROR: nxsem_wait failed: %d\n", ret);
goto errout_with_clone;
}
/* Loop until the device name is verified to be unique. */
while (priv->td_minor < CONFIG_TELNET_MAXLCLIENTS)
{
if (g_telnet_clients[priv->td_minor] == NULL)
{
snprintf(session->ts_devpath, TELNET_DEVPATH_MAX,
TELNET_DEVFMT, priv->td_minor);
break;
}
priv->td_minor++;
}
if (priv->td_minor >= CONFIG_TELNET_MAXLCLIENTS)
{
nerr("ERROR: Too many sessions\n");
ret = -ENFILE;
goto errout_with_semaphore;
}
/* Register the driver */
ret = register_driver(session->ts_devpath, &g_telnet_fops, 0666, priv);
if (ret < 0)
{
nerr("ERROR: Failed to register the driver %s: %d\n",
session->ts_devpath, ret);
goto errout_with_semaphore;
}
/* Close the original psoock (keeping the clone) */
psock_close(psock);
#ifdef CONFIG_TELNET_SUPPORT_NAWS
telnet_sendopt(priv, TELNET_DO, TELNET_NAWS);
#endif
#ifdef CONFIG_TELNET_CHARACTER_MODE
telnet_sendopt(priv, TELNET_WILL, TELNET_SGA);
telnet_sendopt(priv, TELNET_WILL, TELNET_ECHO);
#endif
/* Has the I/O thread been started? */
if (g_telnet_io_kthread == (pid_t)0)
{
/* g_iosem is used for signaling and, hence, must not participate in
* priority inheritance.
*/
nxsem_setprotocol(&g_iosem, SEM_PRIO_NONE);
/* Start the I/O thread */
g_telnet_io_kthread =
kthread_create("telnet_io", CONFIG_TELNET_IOTHREAD_PRIORITY,
CONFIG_TELNET_IOTHREAD_STACKSIZE, telnet_io_main,
NULL);
}
/* Save ourself in the list of Telnet client threads */
g_telnet_clients[priv->td_minor] = priv;
nxsem_post(&g_clients_sem);
nxsem_post(&g_iosem);
return OK;
errout_with_semaphore:
nxsem_post(&g_clients_sem);
errout_with_clone:
psock_close(&priv->td_psock);
errout_with_dev:
free(priv);
return ret;
}
/****************************************************************************
* Name: factory_read
****************************************************************************/
static ssize_t factory_read(FAR struct file *filep, FAR char *buffer,
size_t len)
{
return 0; /* Return EOF */
}
/****************************************************************************
* Name: factory_write
****************************************************************************/
static ssize_t factory_write(FAR struct file *filep, FAR const char *buffer,
size_t len)
{
return len; /* Say that everything was written */
}
/****************************************************************************
* Name: telnet_ioctl
****************************************************************************/
static int telnet_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
int ret = OK;
switch (cmd)
{
#ifdef HAVE_SIGNALS
/* Make the given terminal the controlling terminal of the calling process */
case TIOCSCTTY:
{
/* Check if the ISIG flag is set in the termios c_lflag to enable
* this feature. This flag is set automatically for a serial console
* device.
*/
/* Save the PID of the recipient of the SIGINT signal. */
priv->td_pid = (pid_t)arg;
DEBUGASSERT((unsigned long)(priv->td_pid) == arg);
}
break;
#endif
#ifdef CONFIG_TELNET_SUPPORT_NAWS
case TIOCGWINSZ:
{
FAR struct winsize *pw = (FAR struct winsize *)((uintptr_t)arg);
/* Get row/col from the private data */
pw->ws_row = priv->td_rows;
pw->ws_col = priv->td_cols;
}
break;
#endif
default:
ret = -ENOTTY;
break;
}
UNUSED(priv); /* Avoid warning if not used */
return ret;
}
/****************************************************************************
* Name: telnet_poll
*
* Description:
* The standard poll() operation redirects operations on socket descriptors
* to this function.
*
* Input Parameters:
* fd - The socket descriptor of interest
* fds - The structure describing the events to be monitored, OR NULL if
* this is a request to stop monitoring events.
* setup - true: Setup up the poll; false: Teardown the poll
*
* Returned Value:
* 0: Success; Negated errno on failure
*
****************************************************************************/
static int telnet_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup)
{
FAR struct inode *inode = filep->f_inode;
FAR struct telnet_dev_s *priv = inode->i_private;
FAR struct socket *psock;
DEBUGASSERT(fds != NULL);
/* Get the underlying socket structure and verify that the sockfd
* corresponds to valid, allocated socket
*/
psock = &priv->td_psock;
if (!psock || psock->s_crefs <= 0)
{
return -EBADF;
}
/* Test if we have cached data waiting to be read */
if (priv->td_pending > 0)
{
/* Yes.. then signal the poll logic */
fds->revents |= (POLLRDNORM & fds->events);
if (fds->revents)
{
nxsem_post(fds->sem);
}
}
/* Then let psock_poll() do the heavy lifting */
return psock_poll(psock, fds, setup);
}
/****************************************************************************
* Name: telnet_io_main
****************************************************************************/
static int telnet_io_main(int argc, FAR char** argv)
{
FAR struct telnet_dev_s *priv;
FAR char *buffer;
int i;
int ret;
while (1)
{
nxsem_reset(&g_iosem, 0);
/* Poll each client in the g_telnet_clients[] array. */
nxsem_wait(&g_clients_sem);
for (i = 0; i < CONFIG_TELNET_MAXLCLIENTS; i++)
{
priv = g_telnet_clients[i];
if (priv != NULL && !(priv->td_fds.revents & (POLLHUP | POLLERR)))
{
priv->td_fds.sem = &g_iosem;
priv->td_fds.events = POLLIN | POLLHUP | POLLERR;
priv->td_fds.revents = 0;
psock_poll(&priv->td_psock, &priv->td_fds, TRUE);
}
}
nxsem_post(&g_clients_sem);
/* Wait for any Telnet connect/disconnect events
* to include/remove client sockets from polling
*/
nxsem_wait(&g_iosem);
/* Revisit each client in the g_telnet_clients[] array */
nxsem_wait(&g_clients_sem);
for (i = 0; i < CONFIG_TELNET_MAXLCLIENTS; i++)
{
priv = g_telnet_clients[i];
/* If poll was setup previously (events != 0) */
if (priv != NULL && priv->td_fds.events)
{
/* Check for a pending poll() */
if (priv->td_fds.revents & POLLIN)
{
if (priv->td_pending < CONFIG_TELNET_RXBUFFER_SIZE)
{
/* Take exclusive access to data buffer */
nxsem_wait(&priv->td_exclsem);
buffer = priv->td_rxbuffer + priv->td_pending +
priv->td_offset;
ret = psock_recv(&priv->td_psock, buffer,
CONFIG_TELNET_RXBUFFER_SIZE -
priv->td_pending - priv->td_offset,
0);
priv->td_pending += ret;
nxsem_post(&priv->td_exclsem);
/* Notify the client thread that data is available */
nxsem_post(&priv->td_iosem);
#ifdef HAVE_SIGNALS
/* Check if any of the received characters is a
* control that should generate a signal.
*/
telnet_check_ctrlchar(priv, buffer, ret);
#endif
}
}
/* Tear it down */
psock_poll(&priv->td_psock, &priv->td_fds, FALSE);
priv->td_fds.events = 0;
/* POLLHUP (or POLLERR) indicates that this session has
* terminated.
*/
if (priv->td_fds.revents & (POLLHUP | POLLERR))
{
/* notify the client thread */
nxsem_post(&priv->td_iosem);
}
}
}
nxsem_post(&g_clients_sem);
}
return 0;
}
/****************************************************************************
* Name: factory_ioctl
****************************************************************************/
static int factory_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
int ret = OK;
switch (cmd)
{
/* Command: SIOCTELNET
* Description: Create a Telnet sessions.
* Argument: A pointer to a write-able instance of struct
* telnet_session_s.
* Dependencies: CONFIG_NETDEV_TELNET
*/
case SIOCTELNET:
{
FAR struct telnet_session_s *session =
(FAR struct telnet_session_s *)((uintptr_t)arg);
if (session == NULL)
{
ret = -EINVAL;
}
else
{
ret = telnet_session(session);
}
}
break;
default:
ret = -ENOTTY;
break;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: telnet_initialize
*
* Description:
* Create the Telnet factory at /dev/telnet.
*
* Input Parameters:
* None
*
* Returned Value:
* Zero (OK) on success; a negated errno value on failure.
*
****************************************************************************/
int telnet_initialize(void)
{
return register_driver("/dev/telnet", &g_factory_fops, 0666, NULL);
}
#endif /* CONFIG_NETDEV_TELNET */
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